1. Field of the Invention
The instant disclosure relates to a miniature zoom lens, and more particularly, to a miniature zoom lens applied to an image-capturing device such as DV (digital video), DSC (digital still camera), etc.
2. Description of Related Art
With the rapid development of video technologies, imaging devices such as digital video cameras and digital cameras have found widespread applications. The core element of these imaging devices is a zoom lens. By varying the optical focus of the zoom lens, a clean image can be focused on a charge-coupled device. The optical quality of the zoom lens is closely related to the imaging quality, thus it is very important to improve the quality of the zoom lens.
Moreover, the known zoom lens usually uses CCD or CMOS as an image sensor for achieving 3× zoom ratio, as shown in U.S. Pat. No. 7,339,749, US 2009/0034067, US 2009/0034092, etc. Any one of the related arts uses three lens groups including a first lens group with negative refractive power, a second lens group with positive refractive power, and a third lens group with positive refractive power. The first, the second and the third lens groups are arranged from an object side to an image side of the zoom lens in sequence. However, the three lens groups are movable structure, thus the cost of the zoom lens is increased. In addition, the first lens group is a compensation group, thus the manufacture of the mechanism of the zoom lens is difficult.
Furthermore, some related arts such as U.S. Pat. No. 7,145,730 and US 2009/0052052 disclose an optical system using a right-angle prism that is used to change the optical axis or optical path of the zoom lens by 90 degrees. However, the related arts use more than eight lens and three moved lens groups, thus the cost of the related arts are increased.